1. Field of the Invention
This invention relates to an invention for controlling an electronic fuel spray valve in an engine such as a gas engine, thereby automatically adjusting the exhaust temperatures of cylinders so as to reduce variation between them, and more specifically relates to an engine which can be controlled in this way, and a controlling apparatus and a method for controlling the engine exhaust temperature, which make such control possible.
2. Description of Related Art
In a multi-cylinder engine, the temperatures of the exhausts from the cylinders do not match, and, in engines for commercial use, variation in the exhaust temperatures of the cylinders is presently regulated to less than an average of ±15° C. at a load of 100%. The exhaust temperature of a cylinder which has exceeded this range is adjusted by manually adjusting a gas-adjusting valve of the cylinder, thereby balancing the exhaust temperatures of the cylinders.
However, since the gas-adjusting valve is adjusted at a load of 100%, there is greater variation between the exhaust temperatures of the cylinders at loads other than 100%. Furthermore, even at a load of 100%, the set value of the gas-adjusting valve deviates from its initial setting as years pass, so that the set value may require readjustment. Unless this deviation in the set value due to the passage of time is dealt with, variation in the exhaust temperatures of the cylinders will greatly increase, causing misfire and knocking.
Such misfire and knocking leads to considerable disadvantages when, for example, operating a co-generation system. That is, in a co-generation system, when the engine suffers misfire or knocking, the engine output (the amount of electricity generated by the system) is reduced as a first step of human or mechanical safety procedures, and, as a second step, the engine is stopped; the result of reducing the engine output and stopping operating is not only to cease supplying the expected power, but may sometimes be non-profitable, after compensation claims of power contract infringement (demand-over).
Therefore, a technique for automatically controlling the exhaust temperatures in the cylinders, so as to reliably balance the exhaust temperatures in the cylinders while the engine is operational, is desirable. This technique is also important in, for example, safely and stably operating the co-generation system mentioned above.
This invention has been realized in view of the problems described above, and aims to provide an exhaust temperature control technique which can automatically control variation in the exhaust temperatures of the cylinders, and prevent misfire and knocking by keeping the exhaust temperatures of the cylinders within a predetermined range.